Mammogram or breast ultrasound: which do you need?

You have been told you have dense breasts, or you are under 40 with a worry about one area, or you simply want a check and aren't sure which scan to ask for. It is a common question, and the answer depends mostly on why you want the scan.

For routine screening, a mammogram is usually the starting point. For a new lump, for younger women, or for dense tissue, your doctor may suggest ultrasound instead of a mammogram or alongside it.

If you already know what you need, you can book breast imaging directly, with no referral needed.

What is the difference between a mammogram and a breast ultrasound?

A mammogram uses a low-dose X-ray to image the breast. It is the standard screening test for breast cancer, and it can show changes before they can be felt. A breast ultrasound uses high-frequency sound waves instead, producing real-time images. That makes it good at looking closely at a specific area in dense tissue, and at telling a solid lump from a fluid-filled cyst.

For many women the most complete picture comes from both scans together.

What each scan is for, who it typically suits, and the price

A breast MRI is usually kept for women at high risk, or for a finding that needs more detail, rather than used as a first test.

Why does breast density change which scan is better?

On a mammogram, dense breast tissue shows up white. So can an abnormality. When both look white, small changes are harder to spot, which is why a mammogram is less sensitive in dense breasts.

Density varies between women and changes with age, hormonal status and body composition. If you have been told you have dense breasts, ask your doctor whether adding ultrasound to your mammogram makes sense for you, because ultrasound can show some changes that dense tissue may hide.

Radiologists grade density on a four-point scale from the American College of Radiology's BI-RADS atlas: A is almost entirely fatty, B has scattered areas of dense tissue, C is heterogeneously dense, which can hide small masses, and D is extremely dense. The UK National Screening Committee notes that about 10% of women have very dense breasts and up to 50% have a mix of dense and fatty tissue, and it is reviewing whether extra screening should be offered to them.

A 3D mammogram, or tomosynthesis, is one answer some hospitals use. It takes more X-rays than a standard mammogram and builds them into thin slices, so overlapping tissue hides less. We arrange both the standard two-view mammogram and 3D mammography through our partner imaging centre, and our guide to what happens at a mammogram explains the difference between 2D and 3D. Ultrasound is the other common addition for dense breasts.

Does age affect which scan I should have?

Yes. Women under 40 tend to have denser breast tissue, so ultrasound is usually the first scan for a breast concern at that age. Private screening mammograms are normally offered from age 40. The NHS Breast Screening Programme invites women for a mammogram every 3 years from age 50 to 70, and a private mammogram lets you book outside those ages or intervals. If your family history puts you at higher risk, your doctor can advise. If you would like breast imaging as part of a wider check, our sister clinic, Health Screening Clinic, offers private breast cancer screening.

I have found a lump. Which scan should I book?

Start with a GP. Your doctor examines you and recommends the scan that will tell you most: for a specific lump, especially in younger women, ultrasound is sometimes more informative, while for others a mammogram is the right next step. A GP consultation is £150, and same-day appointments for a breast lump assessment are available. Most patients can then be scanned at a partner imaging centre on the same day as their consultation.

What about pregnancy or breastfeeding?

Ultrasound involves no radiation, so it is usually the first scan for a breast concern during pregnancy or breastfeeding. Mention it when you book and we will arrange the right scan.

Where are the scans carried out?

Both the mammogram and the breast ultrasound take place at a specialist partner imaging centre near the clinic, and we give you the location and preparation details when you book. Your GP consultation and results review happen here at 117a Harley Street. Scans are available Monday to Friday, and neither needs a referral.